如何将USB指定引脚PA11和PA12用作通用GPIO输入呢？

大家好，
首先是一些背景：
我试图在启动时将 USB 指定引脚（PA11 和 PA12）用作通用 GPIO 输入，以此来确定主机是否连接到设备并决定是否运行主代码 - 我会在 DP 和 DM 线路上有外部上拉电阻来帮助实现这一点。在等待制作电路板的同时，我想确保我可以在启动时读取引脚电平——为此我使用了 STM32F0-Discovery 电路板。
这是我遇到问题的地方。我最初尝试将引脚 PA11 和 PA12 设置为带有上拉电阻的输入，然后我会使用“飞线”在 0V 和 5V 之间交替引脚电压。然后我设置代码，使 LED 会根据输入引脚改变状态。代码可以在这里看到：

• /* USER CODE BEGIN Header */
• /**
•   ******************************************************************************
•   * @file           : main.c
•   * @brief          : Main program body
•   ******************************************************************************
•   * @attention
•   *
•   *

  © Copyright (c) 2021 STMicroelectronics.

    * All rights reserved.

•   *
•   * This software component is licensed by ST under BSD 3-Clause license,
•   * the "License"; You may not use this file except in compliance with the
•   * License. You may obtain a copy of the License at:
•   *                        opensource.org/licenses/BSD-3-Clause
•   *
•   ******************************************************************************
•   */
• /* USER CODE END Header */
• /* Includes ------------------------------------------------------------------*/
• #include "main.h"
• /* Private includes ----------------------------------------------------------*/
• /* USER CODE BEGIN Includes */
• /* USER CODE END Includes */
• /* Private typedef -----------------------------------------------------------*/
• /* USER CODE BEGIN PTD */
• /* USER CODE END PTD */
• /* Private define ------------------------------------------------------------*/
• /* USER CODE BEGIN PD */
• /* USER CODE END PD */
• /* Private macro -------------------------------------------------------------*/
• /* USER CODE BEGIN PM */
• /* USER CODE END PM */
• /* Private variables ---------------------------------------------------------*/
• /* USER CODE BEGIN PV */
• /* USER CODE END PV */
• /* Private function prototypes -----------------------------------------------*/
• void SystemClock_Config(void);
• static void MX_GPIO_Init(void);
• /* USER CODE BEGIN PFP */
• /* USER CODE END PFP */
• /* Private user code ---------------------------------------------------------*/
• /* USER CODE BEGIN 0 */
• /* USER CODE END 0 */
• /**
•   * @brief  The application entry point.
•   * @retval int
•   */
• int main(void)
• {
•   /* USER CODE BEGIN 1 */
•   /* USER CODE END 1 */
•   /* MCU Configuration--------------------------------------------------------*/
•   /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
•   HAL_Init();
•   /* USER CODE BEGIN Init */
•   /* USER CODE END Init */
•   /* Configure the system clock */
•   SystemClock_Config();
•   /* USER CODE BEGIN SysInit */
•   /* USER CODE END SysInit */
•   /* Initialize all configured peripherals */
•   MX_GPIO_Init();
•   /* USER CODE BEGIN 2 */
•   /* USER CODE END 2 */
•   /* Infinite loop */
•   /* USER CODE BEGIN WHILE */
•   while (1)
•   {
•     /* USER CODE END WHILE */
•       HAL_GPIO_WritePin(LED_USB_GPIO_Port, LED_USB_Pin, HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_11));
•       HAL_GPIO_WritePin(LED_AXIOM_GPIO_Port, LED_AXIOM_Pin, HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_12));
•     /* USER CODE BEGIN 3 */
•   }
•   /* USER CODE END 3 */
• }
• /**
•   * @brief System Clock Configuration
•   * @retval None
•   */
• void SystemClock_Config(void)
• {
•   RCC_OscInitTypeDef RCC_OscInitStruct = {0};
•   RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
•   /** Initializes the CPU, AHB and APB busses clocks
•   */
•   RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
•   RCC_OscInitStruct.HSIState = RCC_HSI_ON;
•   RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
•   RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
•   RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
•   RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL6;
•   RCC_OscInitStruct.PLL.PREDIV = RCC_PREDIV_DIV1;
•   if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
•   {
•     Error_Handler();
•   }
•   /** Initializes the CPU, AHB and APB busses clocks
•   */
•   RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
•                               |RCC_CLOCKTYPE_PCLK1;
•   RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
•   RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
•   RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
•   if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
•   {
•     Error_Handler();
•   }
• }
• /**
•   * @brief GPIO Initialization Function
•   * @param None
•   * @retval None
•   */
• static void MX_GPIO_Init(void)
• {
•   GPIO_InitTypeDef GPIO_InitStruct = {0};
•   /* GPIO Ports Clock Enable */
•   __HAL_RCC_GPIOC_CLK_ENABLE();
•   __HAL_RCC_GPIOA_CLK_ENABLE();
•   /*Configure GPIO pin Output Level */
•   HAL_GPIO_WritePin(GPIOC, LED_USB_Pin|LED_AXIOM_Pin, GPIO_PIN_RESET);
•   /*Configure GPIO pins : LED_USB_Pin LED_AXIOM_Pin */
•   GPIO_InitStruct.Pin = LED_USB_Pin|LED_AXIOM_Pin;
•   GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
•   GPIO_InitStruct.Pull = GPIO_NOPULL;
•   GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
•   HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);
•   HAL_GPIO_WritePin(GPIOA, GPIO_PIN_11|GPIO_PIN_12, GPIO_PIN_SET);
•   /*Configure GPIO pin : PA11 */
•   GPIO_InitStruct.Pin = GPIO_PIN_11;
•   GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
•   GPIO_InitStruct.Pull = GPIO_PULLUP;
•   HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
•   /*Configure GPIO pin : PA12 */
•   GPIO_InitStruct.Pin = GPIO_PIN_12;
•   GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
•   GPIO_InitStruct.Pull = GPIO_PULLUP;
•   HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
• }
• /* USER CODE BEGIN 4 */
• /* USER CODE END 4 */
• /**
•   * @brief  This function is executed in case of error occurrence.
•   * @retval None
•   */
• void Error_Handler(void)
• {
•   /* USER CODE BEGIN Error_Handler_Debug */
•   /* User can add his own implementation to report the HAL error return state */
•   /* USER CODE END Error_Handler_Debug */
• }
• #ifdef  USE_FULL_ASSERT
• /**
•   * @brief  Reports the name of the source file and the source line number
•   *         where the assert_param error has occurred.
•   * @param  file: pointer to the source file name
•   * @param  line: assert_param error line source number
•   * @retval None
•   */
• void assert_failed(char *file, uint32_t line)
• {
•   /* USER CODE BEGIN 6 */
•   /* User can add his own implementation to report the file name and line number,
•      tex: printf("Wrong parameters value: file %s on line %drn", file, line) */
•   /* USER CODE END 6 */
• }
• #endif /* USE_FULL_ASSERT */
• /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
  

无论我向引脚施加什么电压/逻辑电平，LED 都不会改变状态。
然后我将 PA11 和 PA12 设置为输出推挽，使它们写入高电平，并使用逻辑分析仪来确定引脚范围。通过这种设置，引脚应该输出逻辑 1，但它们仍为 0！
简而言之，我似乎无法将这些引脚用作常规 GPIO。我曾尝试查看文档以查找对此行为的任何参考，但一无所获。我知道这不是我设置引脚的方式，因为将相同的过程/配置应用于 PA9 和 PA10 会产生预期的结果。
有任何想法吗？